class  DengJi{
	public static void main(String[] args) {
		int a=83;
		if(a>=80 && a>=100){
		 System.out.println("A");
		
		}else if(a>=70 && a<=79){
		  System.out.println("B");
		
		}else if(a>=60 && a<=69){
		  System.out.println("c");
		
		}else if(a>=0 && a<=69) {
			System.out.println("D");
		}




	}
}
